The sense of body ownership refers to the attribution of the body or body parts to oneself. Proprioceptive drift is a phenomenon in which the perceived position of a body part changes during body ownership illusions. These two metrics—the subjective level of body ownership and proprioceptive drift—have been widely used as corresponding subjective and behavioral measures. However, discrepancies between these metrics have been reported, and the conditions under which they align remain unclear. We focused on the relative positioning of a visually presented dummy hand and an unseen actual hand. In an immersive virtual reality environment, we examined the relationship between subjective body ownership toward a virtual hand and proprioceptive drift. Three spatial configurations were compared by varying the mediolateral position of the dummy hand, with a spatially aligned condition serving as a baseline, and with an additional manipulation of temporal delay between the actual and virtual hands. The results showed that when the dummy hand was placed 0.1 m medial to the actual hand, the correlation between body ownership and proprioceptive drift was not statistically significant (correlation coefficient = 0.047). Under this medial condition, subjective ownership decreased with increasing delay, whereas proprioceptive drift persisted despite temporal asynchrony. In contrast, when the dummy hand was placed 0.1 m lateral to the actual hand, a significant positive correlation was observed between body ownership and proprioceptive drift (correlation coefficient = 0.49). Further analysis using a linear mixed-effects model suggested that these differences in correlation were associated with laterality-dependent effects of temporal delay on body ownership and proprioceptive drift. These findings highlight the importance of considering both spatial configuration and temporal factors when interpreting the relationship between body ownership and proprioceptive drift in virtual reality environments.
Kawaguchi et al. (Mon,) studied this question.